Supervisors: Neil Davies (Earth Sciences) and Sanjeev Gupta (Imperial College, London)
Importance of the area of research:
Conceptual models regarding the facies and architecture of marine sedimentary rocks are biased towards strata deposited on Earth after the evolution of land plants. In order to identify a universal signature of marine deposits, which could be applied to ancient strata on unvegetated extraterrestrial bodies, it is necessary to understand the ways in which non-actualistic marine sedimentary systems operated prior to (and during) the greening of the Earth’s continents. Pre-vegetation seas may have borne little resemblance to their modern counterparts: wildly different levels of terrigenous sediment flux would have had major impacts on the sedimentary facies and architecture of clastic marine systems. An holistic assessment of Palaeozoic siliciclastic marine facies is required to (1) complete crucial insights into the Earth System effects of evolving vegetation, and (2) to understand the visually diagnostic traits of pre-vegetation marine strata for the purpose of their identification on other planets.
Sedimentary systems operating outside of the influence of vegetated continents are viewed as non-actualistic due to their rarity on Earth at the present day. However, on many other planets, and for most of Earth history, such systems were the norm. In the Precambrian and Lower Palaeozoic, prior to land plant evolution, terrestrial sedimentary facies are poor in fines compared to their younger counterparts, leading to a profound question: if mud was being produced on land, where did it end up, and how did it affect the marine realm? Pre-Silurian terrigenous marine facies may be suspected to hold the answer.
What the student will do:
Extensive meta- analysis of trends within published literature will be combined with focussed original fieldwork on Precambrian and Lower Palaeozoic marine successions (in the UK and North America) in order to advance conceptual sedimentological models for marine systems operating in the absence of land plants. The student will identify, compile and manage a dataset of secular facies changes within terrigenous marine rocks of these ages, through the means of a comprehensive literature review. Statistical analysis of individual parameters within this dataset will follow, identifying trends within the global marine physical sedimentary record and comparing trend timelines with the fossil record of both land plant and marine ecosystem evolution. Ground-truthing of observed trends will be completed through extensive original fieldwork into multiple sedimentary successions. Visual comparison with imagery data of presumed aqueously deposited rocks from extraterrestrial bodies will further promote a model for pre-vegetation marine deposits.
Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.
Davies, N.S., & Gibling, M.R., 2010. Cambrian to Devonian evolution of alluvial systems: The sedimentological impact of the earliest land plants, Earth-Science Reviews, vol. 98, pp. 171-200.
Davies, N.S., & Gibling, M.R., 2013. The sedimentary record of Carboniferous rivers: Continuing influence of land plant evolution on alluvial processes and Palaeozoic ecosystems, Earth-Science Reviews, vol. 120, pp. 40-79.
Gibling, M.R., & Davies, N.S., 2012. Palaeozoic landscapes shaped by plant evolution, Nature Geoscience, vol. 5, pp. 99-105.
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